Ectoparasites are organisms that live in or on the skin of a host and derive sustenance from that host. Ectoparasites are a worldwide problem as to health. Problems with ectoparasites result in economic consequences for both human and animal populations.
Ectoparasites include biting or vesicating arthropods and are divided into insect and arachnid groups. Insects include lice, bedbugs, fleas and flies. Arachnids include mites, ticks and spiders.
Ectoparasites transmit various diseases including bacterial, spirochetal, viral, rickettsial, helminthic and protozoal. The following provides an example of ectoparasites and their related diseases:
______________________________________ Ectoparasite Disease ______________________________________ Ticks Hard Ticks Hypersensitivity to bites with fever, pruritus and urticaria. Paralysis Granuloma Lyme Disease Q Fever Tularemia Babesiosis Rocky Mountain Spotted Fever Ehrlichiosis Soft Ticks Endemic Relapsing Fever Human Body Lice Epidemic Relapsing Fever 2 to 4 mm parasites Epidemic Typhus Trench Fever Mosquitos Yellow Fever Encephalitis Dengue Fever Brugia Malayi Filariasis Malaria Flies Leishmaniasis Onchocerciasis Trypanosomiasis Tularemia Fleas and Lice Murine Typhus Plague Mouse Mites Rickettsial Pocks Mites Scrub Typhus Scabies 0.35 mm organism ______________________________________
Principles and Practice of Infectious Disease, Third Edition, Mandell, Douglas, Bennett.
Elimination of the various ectoparasites is generally not possible. For example, Lyme disease is carried by what is often referred to as the deer tick. This tick is found in wooded regions wherein there are fairly large populations of deer, rabbits, and other animals. The deer ticks can only be avoided with certainty by staying away from these areas. The areas provide a large reservoir of wild animals that harbor the Lyme disease carrying ticks. Similarly, eradication methods have been relatively unsuccessful in controlling various ectoparasites. Insecticides and environmental manipulation can help to decrease populations of the ectoparasites. However, use of insecticides can have other effects such that the use of insecticides has raised new concerns with regard to resistance to the insecticides by the organisms, environmental damage and personal health concerns with regard to topical insecticides and other agents.
As removing all of the host animals from an area of human and domesticated animal populations is not possible (such as removing all deer and rabbits, etc.), little can be done to fend off diseases carried by ectoparasites, including Lyme disease. Experts have advised that people living in areas wherein particular ectoparasites are present, such as Lyme disease carrying deer ticks, wear clothing so as not to expose skin, and to check for the ectoparasites, after coming in from out of doors. Unfortunately, certain ectoparasites, including deer ticks, are very small.
Deer ticks in their larvae stage are under one half millimeter in size. Similarly, deer ticks in their nymph stage are also small, approximately one half millimeter in size. Detection of these ectoparasites can be quite difficult, particularly detection under human hair, such as ectoparasites which have gotten to human skin, under the cover of human hair, such as the human scalp or the skin of an animal such as a pet.
Removal of the ectoparasite from the skin is always necessary to prevent disease transmittal. As this requires careful and frequent inspection of the skin and hair, the process can be very difficult and time consuming. The process is especially difficult with regard to children, long-haired individuals or restless pets. Parasites, including deer ticks, can be small, hidden in hair and hard to see with the naked eye.